Silicon carbide is a desirable material for high power and temperature bipolar and unipolar electronic devices, such as high blocking voltage PIN and Schottky diodes, respectively. Other such devices include, but are not limited to, junction barrier Schottky diodes (“JBS”), merged-PIN-Schottky diodes (“MPS”), double-diffused metal-oxide-semiconductor field effect transistors (“DMOSFETS”), vertical junction field effect transistors (“VJFETs”), bipolar junction transistors (“BJTs”) and insulated-gate bipolar transistors (“IGBTs”). However, the presence of basal plane dislocations (“BPDs”) in the drift layer of bipolar or unipolar devices, where bipolar injection may occur, leads to the creation of Shockley stacking faults (“SSFs”) when electron-hole pairs (“ehps”) are injected via either electrical bias or optical excitation. The SSFs are 3C—SiC (cubic) in structure and act as ‘structure-only’ quantum wells within the larger bandgap 4H—SiC (hexagonal) lattice. Continued ehp injection during forward bias or optical excitation causes these SSFs to continue to expand throughout the drift layer, which in turn induces an increase in the forward voltage drop (Vf). Furthermore, SSFs have been found to be the cause for the observed increase in the specific on-state resistance of SiC high-power depletion-mode DMOSFETS.
Recent experiments by the Applicants and Miyanagi et al., illustrated that expanded SSFs within PIN diodes and n− epitaxial layers, respectively, were contracted back to the original BPDs from which they nucleated via annealing in nitrogen gas at temperatures between 300-700° C. in the absence of an applied current. Miyanagi et al., Annealing Effects on Single Shockley Faults in 4H—SiC, Applied Physics Letters 89, 062104 (2006) is incorporated herein by reference. These and other disproving studies by the Applicants and Miyanagi et al. provide evidence for a driving-force model reported by the Applicants that explains the mechanism, energetics and kinetics associated with SSF expansion and contraction. Other studies have reported observing the shrinking of SSFs under very low electrical injection conditions. While these measurements clearly renewed the important questions concerning the driving force for SSF propagation, it was unclear at the time whether the annealing causes an associated recovery of the drift in Vf and whether there is any lasting damage resulting from subsequent stresses and anneals, and what the correlations between the SSF propagation and the Vf drift are.